This invention relates to a closed reinforcement fibre package consisting of a material disintegratable in fibre concrete, whereby the reinforcing fibres are present in a loose form in this package and whereby the reinforcing fibres are applied in a substantially mutually parallel position in this package.
Such a closed reinforcement fibre package is described in WO 01/81265, which document belongs to the prior art according to article 54(3)EPC.
Closed reinforcement fibre packages consisting of a material disintegratable in fibre concrete, whereby the reinforcing fibres present in a loose form in these packages are also known from DE-A-4.214.540 and WO 95/11861.
A disadvantage of the addition of reinforcing fibres in a loose form during the concrete mixing operation for forming fibre concrete is that this process often results in a non-uniform dispersion or distribution of the reinforcing fibres in the formed fibre concrete.
It is therefore important that the reinforcing fibres are applied in a substantially mutually parallel position in this package, as already mentioned in WO 01/81265.
Moreover, it is also very important that the reinforcing fibres in the closed packages maintain their mutually parallel position during the transport of these packages.
Therefore, the invention proposes for a closed reinforcement package mentioned in the opening lines that the filling degree of the reinforcing fibres in the closed package is at least 75 %.
Preferred embodiments of the closed reinforcement fibre package according to the invention are characterised in that the length of the reinforcing fibres substantially corresponds to the length of the package and that the fibres are situated lengthwise the package or that the length of the reinforcing fibres substantially corresponds to the width of the package and that the fibres are situated widthwise in the package.
It has now been found that an improved distribution or dispersion of the reinforcing fibres is obtained during the mixing operation of the fibre concrete when the loose reinforcing fibres are supplied into the concrete mixer in a substantially mutually parallel position or in closed packages according to the invention.
It has to be noted that it is already known to pack such reinforcing fibres in a substantially mutually parallel position. This is a.o. described in BE-A-1.003.656 (8901350). In this case, the ends of the parallel reinforcing fibres are coated and connected to each other a.o. by a special glue.
This is also described in WO 96/02715. In this case, the parallel reinforcing fibres are surrounded by a special casing material, whereas the ends of the parallel reinforcing fibres are not coated or surrounded by a casing material.
In the package according to the invention, the filling degree of the reinforcing fibres in the closed package is at least 75 %.
In another preferred embodiment of the package according to the invention, the reinforcing fibres are steel fibres.
By fibre concrete, we understand all curing materials, provided with reinforcing fibres, such as steel fibres, glas fibres and synthetic fibres, such as polypropylene fibres to improve the properties of the curable material.
This invention further relates to a chain packing consisting of a number of closed packages according to the invention.
In a preferred embodiment of the chain packing according to the invention, the packages are joined to each other.
In still a further preferred embodiment of the chain packing according to the invention ; the packages are joined in line to each other.
A great advantage of such a chain packing according to the invention is that it is now possible to supply an exact quantity of reinforcing fibres to the mixing silo or concrete mixer in a very simple way.
The supply of the exact quantity of reinforcing fibres, such as steel fibres, is extremely difficult. This is certainly the case when the mixture operation is carried out on the building site itself.
Numerous solutions have already been proposed, such as EP-A-522.029 (WO 91/14551) ; EP-A-499.572 ; EP-A-499.573 ; DE 29714704U ; DE-A-3.412.216 ; DE-A-4.427.156 ; FR-A-2.672.045 and many other patent documents.
A disadvantage of these known solutions is that they all need a rather complex dosing machine or weighing machine.
Another disadvantage is that the dosing or weighing of reinforcing fibres in a concrete mixing plant or on a building yard is a cumbersome and time-consuming operation.
Thanks to the use of such a chain packing according to the invention; it is now possible to supply an exact quantity of reinforcing fibres to the mixing silo or concrete mixer in a very simple way. It is now possible to supply a correct, well-defined quantity of reinforcing fibres in the closed packages, such as sacks, during the manufacturing of the reinforcing fibres. This makes it possible to supply the exact quantity of reinforcing fibres to the mixing silo by means of a conveyor belt, a roll system or a similar alimentation device, in which the former dosing or weighing operations are replaced by a measuring operation of the length of the continuous chain packing or a counting operation of the number of supplied packages to the mixing silo.
The invention will be further explained in the following description by means of the accompanying drawing.
In the drawing, figures 1 and 2 give a representation, both schematically and in perspective of the closed fibre packages and parts of the chain packing according to the invention.
In figure 1, the chain packing according to the invention is generally indicated by 1. The chain packing consists of a large number of sacks 2 that are joined together. The sacks 2 may be made of a material that can be disintegrated in mortar or concrete. The sacks or packings 2 are completely closed.
As already mentioned above, it is already known to mix ingredients in concrete, stored in sacks, such as e.g. cellulose, which disintegrate in water. Preferably, a cellulose-based foil is used for the sacks 2 ; such foil will also be used as basic material for paper, possibly, such as known in the paper branch of industry, with addition of water-soluble glue and fillers, which are harmless to the concrete. The sacks can e.g. be glued together and closed with water-soluble heat-adhesive. But it is clear that every foil that distintegrates in the concrete water within the usual mixing time can be used.
In figure 1, the reinforcing fibres, packed in the sacks 2, are indicated by 3. The reinforcing fibres 3 can be made of all sorts of materials. This depends on the demands required of the fibres and on the fibre concrete to be reinforced. Preferably, steel reinforcing fibres 3 are used, sold amongst others by the applicant N.V. Bekaert S.A. under the brand name DRAMIX. Mostly, steel fibres 3 are used with a tensile force comprised e.g. between 500 and 3000 N/mm2.
The used fibres can e.g. be straight. This is the simplest and cheapest version of reinforcing fibres that can be used for reinforcement. Preferably, the reinforcing fibres 3 have a form that makes it rather difficult to pull them out of the cured concrete material using a tensile strain. To that end, the fibres are e.g. corrugated or their cross-section-surface varies along the length. For steel fibres, the thickness or diameter preferably varies from 0.15 to 1.2 mm. The length-to-diameter ratio for steel fibres is, for practical and economical reasons, mostly situated between 10 and 200 and preferably minimally amounts to 40. For non-straight fibres, the length is the rectilinear distance between the ends of the fibres, whereas the diameter of fibres of which the diameter varies along the length is defined as the average diameter over the entire length.
As figure 1 shows, the reinforcing fibres 3 are preferably situated in a substantially mutually parallel position in the sack 2. In the event of steel fibres, the weight of the total number of fibres per sack 2 varies between 100 grams and 2 kg. It is also possible to use without any problems sacks weighing more than 2 kg.
The packing and weighing of steel fibres, such as described above, can be executed in line with the actual production of the steel fibres or on another spot, separated from the actual manufacturing of the steel fibres. It is e.g. possible to place the steel fibres 3 in a mainly mutual parallel position by means of magnetic forces.
Preferably, the length of the steel fibres 3 is practically identical to the length of the sack 2 and the steel fibres 3 are situated lengthwise the sack 2. The chain packing 1 preferably consists of sacks 2 that are joined in line. It is also possible to make sure that the length of the steel fibres 3 is practically identical to the width of the sacks 2 and that the fibres 3 are situated widthwise the sack 2.
Preferably, the packages or sacks 2 are substantially completely filled with the reinforcing fibres 3 so that the fibres 3 maintain their mutually parallel position during transport of the packages 2. It has been found that the filling degree of the reinforcing fibres 3 into the packages 2 should be at least 75 % to maintain the mutually parallel position of the fibres 3 during the transport of the packages 2. By filling degree is understood the proportion or ratio between the volume of reinforcing fibres 3 and the volume of the sack or package 2.
It is obvious that the chain packing 1 according to the invention makes it now possible to easily supply such continuous packings 1 to the mixing silo by means of simple means of transportation, such as a conveyor belt, allowing in a simple way by means of a counter to count the number of sacks 2 or by means of a simple measuring device to measure the length of the supplied chain packing in order to easily define the supplied weight of reinforcing fibres 3 to the mixing silo.
Figure 2 shows a chain packing 1, whereby the packages or sacks 2 are connected by means of one side thereof to a tape or strip 4. The strip 4 can be replaced by a wire, a cord or the like. The strip 4 is made of a material disintegratable in the concrete to be reinforced.